Human Thermal Comfort Conditions Research Articles

A Comparative Analysis of Outdoor Thermal Comfort Indicators Applied in China and Other Countries

Outdoor thermal comfort is an important criterion for evaluating the quality of outdoor activity environments and is also a significant indicator for assessing sustainable building design. Over the past century, more than 165 indoor and outdoor thermal comfort indexes have been developed to define human thermal comfort conditions under various circumstances and to quantify indoor and outdoor thermal environmental conditions. However, in the process of outdoor thermal comfort indicators becoming widely used worldwide, it remains a pressing research issue to compare the current state of application in China and other countries, identify the key areas of application for both sides, and outline the trends in outdoor thermal comfort index application. This study analyzed 346 articles on outdoor thermal comfort indicators. Employing bibliometric methods, we outline the general landscape of outdoor thermal comfort index applications in China and other countries. Additionally, we utilize comparative analysis to uncover similarities and differences in the research focus on outdoor thermal comfort. The research findings indicate the following: (1) Compared to China, other countries started outdoor thermal comfort index application research earlier. Their papers have higher average citation counts and engage in close academic collaborations. However, the quantity of published papers is fewer than in China. (2) The top five frequently used indexes in both China and other countries are PET (including mPET), UTCI, PMV, SET* (including OUT_SET*), and THI (including DI). China tends to use PET and UTCI more frequently than other countries. (3) The potential future directions for outdoor thermal comfort index applications in both China and other countries include: “monitoring and controlling regional outdoor thermal comfort at the temporal and spatial scales”, “multi-factors coupling effects on outdoor thermal comfort”, “human health assessment and prediction based on outdoor thermal comfort”, and “utilizing computational algorithms to calculate outdoor thermal comfort”. This study can serve as a reference for researchers and designers in the industry, contributing to the creation of sustainable outdoor environments.

Simulating the effect of urban sprawl on air quality and outdoor human thermal comfort in a cold city, Erzurum, Turkey.

Research on climate-sensitive urban planning is important to improve the quality of city life. Cold climate cities should respect climatic characteristics to diversify outdoor uses and increase air quality to maximize the benefits of winter. This study is aimed to explore the impact of changing urban pattern on air pollution and outdoor human thermal comfort conditions (HTCCs) in a newly developed urban area in Şükrüpaşa neighbourhood, Erzurum, among the coldest cities in Turkey, with high PM10 and low HTCCs levels. Sensitivity of urban development pattern to climate conditions and its suitability to eliminate the winter disturbances caused by HTCCs and air pollution were investigated by producing maps for HTCCs and air pollution using morphological, meteorological and spatial data and ENVI-met model in winter period of 2017 and 2022. It was found that newly developed areas increase the unfavourable conditions in terms of air quality, temperature and HTCCs due to the reasons like improper land uses, urban sprawl, high urban density and ventilation problems. In high-elevated cold cities, spatial planning and design principles should strictly be followed by incorporating climate knowledge and without revising the spatial decisions.

Optimization design of waterfront tour routes under thermal comfort assessment in summer—a case study of West Lake in Hangzhou, China

ABSTRACT The existing research on waterfront tour route planning suggests that thermal comfort assessment has a direct impact on people’s outdoor tour experiences. It contributes to understanding the thermal comfort regulation mechanisms of landscape nodes and the scientific planning of tour routes. However, the research in this area is relatively limited and faces complex issues in data processing and analysis. This study takes the West Lake waterfront tour route in Hangzhou, China, as an example. Through empirical research, it validates the feasibility of tour route planning guided by thermal comfort. It employs field surveys, on-site measurements, and data analysis methods primarily based on the Rayman software to explore the relationship between urban outdoor waterfront spaces and microclimates. The study reveals the following findings: (i) Extensive water bodies surrounding an area positively regulate local microclimates. The closer one is to the water and the more water surrounds the area, the stronger the microclimate effect. (ii) Factors such as spatial openness, waterfront orientation, prevailing monsoons, etc. all have certain impacts on the microclimates of the lake and lakeside spaces. (iii) Air temperature has significant variability in its impact on human thermal comfort, with different PET (Physiological Equivalent Temperature) values at each measurement point during different time periods. The study combines the actual human thermal comfort conditions at eight measurement points around the lake with existing tour routes. It proposes two practical tour route optimization designs based on real tour microclimate factors. These designs employ thermal comfort assessment methods to effectively enhance and improve human thermal comfort during tours. This research carries social value and provides new insights for mitigating urban waterfront space microclimates, enhancing tour comfort, and improving landscape environments.

A Methodology to Improve Energy Efficiency and Sustainability in Urban Environments

This paper presents a methodology to improve energy efficiency and sustainability in urban environments. The ongoing climate change is causing increasingly important consequences for cities and their inhabitants. Temperatures are rising and human thermal comfort conditions are becoming worse. For this reason, it is essential to evaluate how parts of cities react to these phenomena and how they could improve their behavior. To do this, the area of interest has to be analyzed from various aspects, starting with an assessment of the microclimatic conditions. Through these analyses, it is possible to observe the interactions between climate and the urban context on a macro-scale. The actual results, such as surface temperature and air temperature, will be useful for hypothesizing where different paved surfaces need to be restored with mitigative actions. Another aspect that needs to be considered for a comprehensive analysis of the area’s potential concerns the study of solar potential. We will describe how this topic was approached, making in-depth evaluations of the quality of the results obtained through the analysis of simplified models. The portability of these data within a spatial domain was also evaluated, integrating the values on a territorial database. Another important topic that needs to be analyzed to plan an improvement of an area in terms of energy production is the installation of new solar active production systems. The appropriate inclusion of photovoltaic panels could lead to the near self-sustainability of buildings by decreasing the external energy demand. The results obtained by applying the methodology in a case study highlight that all these aspects must be taken into account simultaneously to improve the existing conditions of entire city areas, leading to a more sustainable urban environment.

Temporal distribution of human thermal comfort conditions in and around Diyarbakır city, Turkey

Temporal distribution of human thermal comfort conditions in and around Diyarbakır city, Turkey

Analysing daytime summer thermal comfort conditions for Turkey's third largest tourism destination.

Tourism is one of the most vulnerable sectors to climate change since outdoor leisure activities are only possible in appropriate climate conditions for them. Among several climate or weather-related factors effective on tourist satisfaction, the concept of outdoor thermal comfort conditions gains importance with climate change because it is the combined effect of all atmospheric conditions on human body. Therefore, tourism-climate indices to reflect the favourability of destinations begin to include this parameter as a component. Mediterranean basin harbours world famous summer and cultural tourism destinations among others and climate change is expected to impact the region which covers the third largest primary destination of Turkey. The aim of this study is to analyse human thermal comfort conditions in the southwest part of Turkey, world-famous summer tourism region using Physiologically Equivalent Temperature (PET) and Mean Radiant Temperature (Tmrt) values and Geographic Information System (GIS) as a tool to show their spatial distribution as a component of tourism climate indices. As the result of the study, the most influential factors on human thermal comfort conditions in the region are mean radiant temperature, moisture content, air movement and increasing dense urbanisation in 12 districts, where meteorological measurements were taken. As the result of the study, suggestions were proposed to reduce the effect of higher PET and Tmrt values on tourists in the study.

Human Thermal Comfort Conditions during Heat Wave Events in Kyiv, Ukraine

Assessment of the big cities bioclimate during heat wave (HW) events is a highly topical issue and a focus point for many researchers. Reliable results of the assessment of heat stress (HS) intensity during HWs form the basis for the development and implementation of heat adaptation measures. In Ukraine, first HW studies started only a few years ago, and the thermal comfort conditions during these atmospheric phenomena have not been explored yet. The purpose of this article is to assess characteristic features of thermal bioclimate in Kyiv during heat wave events. The assessment is based on the thermal index – physiologically equivalent temperature (PET). The RayMan model was used to simulate PET values. As shown in the study, during the period of 1961–2020, 24 heat wave events were observed in Kyiv. Those HWs were characterized by different duration (from 6 to 18 days) and intensity (with the maximum value of cumulative Ta,MAX 108.6°C). Thermal comfort conditions registered during heat waves were characterized by heat stress varying from slight (23.7°C) to extreme (47.0°C). To assess the impact of HWs on the human, a classification based on mean PET values during a single heat wave and its duration was proposed. According to this classification, heat waves belong to three following grades: HWs with moderate, strong, and extreme HS. Analysis of HW events in Kyiv for the research period demonstrates four (4) heat waves with moderate heat stress, nineteen (19) with strong stress, and one (1) with extreme stress (specifically, the heat wave in late July–first half of August 2010). The daily PET values at 12 UTC during this HW varied from 37°C to 47°C and were much higher than mean PET values for these days during 2005 and 2014.

The Use of Cool Pavements for the Regeneration of Industrial Districts

Industrial districts are characterized by the presence of low and extensive building volumes and by predominantly sealed, impermeable surfaces, which contribute to several environmental problems and to the deterioration of outdoor human thermal comfort conditions, especially during summer hot days. To tackle these issues, this study proposes an approach for the regeneration of industrial districts based on the application of cool materials. Reflective and evaporative pavements were selected as suitable solutions to reduce summer overheating, while ensuring the functionality required by the industrial production, and contributing to stormwater management. The effectiveness of the approach was tested in a portion of the industrial district of Padua (Italy). In summer conditions, the replacement of conventional pavements with cool materials results in a reduction of the ground surface temperatures up to 14.0 °C and a consequent decrease of the air temperature at pedestrian level between 0.6 and 1.2 °C. The effects of human thermal comfort conditions highly depend on the selected cool material and on the morphology of the urban canyon. Finally, the reduction of external surface and air temperatures also contributes in cooling indoor spaces (average decrease from 1.0 to 2.5 °C), with impacts on the energy efficiency of the industrial buildings.

A solar regenerated liquid desiccant evaporative cooling system for office building application in hot and humid climate

In this paper, we provide the thermal analysis and design methodology of a liquid desiccant assisted dew point indirect evaporative cooling system. The purpose of the system is to serve as an alternative for conventional vapour-compression based building air conditioning systems in providing satisfactory human thermal comfort conditions in the hot and humid climatic regions. The main features of the study are the following: i) novel incorporation of a forced parallel flow direct solar regenerator and a dew point indirect evaporative cooler within the same air conditioning unit; ii) detailed thermal modelling of each of the system components with fewer simplifying assumptions compared to earlier works; iii) large cooling capacity (~18.8 TR) under harsh climate; and, iv) a comprehensive year-round case study for system operation in a hot and humid location (Kolkata, India). Our thermal model is validated with a reference model study. The maximum room air temperature predicted by the current system for year-long analysis is 26.7 °C. The thermal COP of the system for diurnal operation in the most humid month of a calendar year (July) varied between 0.40 and 0.96. The cooling system can prevent overheating of the conditioned space, as specified by ASHRAE Standard 55–2017, throughout the year.

Solar assisted cooling rule in indoor air quality

<p>Indoor air quality as always is the centre of attention for researchers, architect developers and public health officials. As every-one know. The human exposure to a variety of indoor pollutants and the high cost of energy are the motivation for these kinds of studies. Fungus and mould growth has always been a problem in subtropical climate areas due to the high temperature and high humidity. Generally in institutional buildings, most of the internal heat load is generated by human body and thermal comfort is achieved with extensive usage of recycled air and air conditioning. The main considerations in any air conditioning system economisers are based on the usage of recycled air and air ventilation. The current practice in an institutional building cooling system under subtropical climate is to curb the mould issue by overcooling large recirculation airflow to remove the moisture content from the air, which is considered as an expensive practice. The use of a solar desiccant cooling system to reduce moisture from the air and to improve indoor air quality is found to be economical, environmental friendly and readily achievable in the tropics. This technology is the future alternative to the conventional vapour compression cooling system to maintain human thermal comfort conditions and enhance indoor air quality. Solar desiccant cooling systems are also environmentally friendly and energy efficient. This paper presents review on a solar desiccant cooling system and its effect on indoor air quality. It first introduces the issue of air moisture, mould growth and indoor air quality and then the development and application of thermally activated desiccant cooling technologies.</p>

Spatial Patterns of Human Thermal Comfort Conditions in Russia: Present Climate and Trends

AbstractThe assessment of bioclimatic conditions at the national scale remains a highly relevant task. It might be one of the main parts of the national strategy for the sustainable development of different regions under changing climatic conditions. This study evaluated the thermal comfort conditions and their changes in Russia according to gridded meteorological data from ERA-Interim reanalysis with a spatial resolution of 0.75° × 0.75° using the two most popular bioclimatic indices based on the human energy balance: physiologically equivalent temperature (PET) and universal thermal comfort index (UTCI). We analyzed the summer and winter means of these indices as well as the repeatability of different thermal stress grades for the current climatological standard normal period (1981–2010) and the trends of these parameters over the 1979–2018 period. We revealed the high diversity of the analyzed parameters in Russia as well as significant differences between the contemporary climate conditions and their changes in terms of mean temperature, mean values of bioclimatic indices, and thermal stress repeatability. Within the country, all degrees of thermal stress were possible; however, severe summer heat stress was rare, and in winter nearly the whole country experienced severe cold stress. Multidirectional changes in bioclimatic conditions were observed in Russia against the general background of climate warming. The European part of the country was most susceptible to climate change because it experiences significant changes both in summer and winter thermal stress repeatability. Intense Arctic warming was not reflected in significant changes in thermal stress repeatability.

Sensitivity analysis and multi-objective optimization of energy consumption and thermal comfort by using interior light shelves in residential buildings

Abstract Sunlight is one of the most accessible environmental agents which has been used as primary energy source. In current study, the effect of daylight distribution in interior spaces on human thermal comfort conditions and energy consumption in the residential buildings is investigated based on light shelf using simulation methods and tools. Firstly, a comprehensive parametric study is presented to examine the impact of light shelf design parameters (including angle, depth and number of the light shelves) on two objective functions of building’s total energy consumption (including heating, cooling and electrical energy) and predicted percentage of dissatisfied people. Then, employing genetic algorithm, a multi-objective optimization is conducted in order to minimize the two objective functions simultaneously. Light shelves are evaluated for three orientations of West, South and East; horizontally and vertically. Results show that the optimum angle, depth and number of light shelves for West orientation are 24.37°, 0.571 m and 5, respectively; for South orientation are 89.62°, 0.295 m and 4, respectively; for East orientation are 36.51°, 0.659 m and 4, respectively. In addition, results indicate that optimum conditions of light shelves decreases the total heating, cooling and electrical energy consumption by 27.819 kWh/m2, 49.176 kWh/m2 and 34.853 kWh/m2, respectively.

An evaluation process for natural ventilation using a scenario-based multi-criteria and multi-interaction analysis

This study examines natural ventilation with respect to human thermal comfort conditions using a scenario-based, multi-criteria, and multi-interaction analysis. The proposed methodology evaluates the design development process in terms of decisions on building physics and building geometry during the early design stages to maximize human thermal comfort conditions and reduce cooling load requirements. The methodology integrates a detailed three-dimensional (3D) building and computational fluid dynamics (CFD) modeling within a building information modeling (BIM) platform during the design development stage, which is developed and structured to optimize the evaluation process. The operational characteristics of the building in respect of windows and shutters have important effects on natural ventilation, which in turn influences thermal comfort, and cooling load. Thus, the multi-interaction analysis of natural ventilation is considered with operational schemes of enveloping that are integrated into a 3D model of the building, which is further transformed to a CFD model. Then, four scenarios using a manually operated building opening are created using the BIM platform. Thus, multi-interactions are achieved by developing a 3D-building model, that not only include the building’s functions and physical specifications but also incorporates the envelope’s thermal capacity coupled with openings that have various operational scenarios for natural ventilation. The results show that the correlation between the air temperature and velocity can provide a comfort zone and decrease the cooling load for energy consumption. The numerical results for one scenario 2 show that if the temperature and velocity values are increased together, human sensation as predicted mean vote (PMV) ranges from 0 to 2, which is considered tolerable for summer comfort, whilst the cooling load is reduced by almost 3%.

Application of Human-biometeorological Comfort Conditions in Köppen-geiger Climate type for Different Cities of Gangetic West Bengal

Gangetic West Bengal (GWB) belongs to Aw climate type after Köppen-Geiger climate classification (KGC). Human thermal comfort (HTC) and vapour pressure (VP) conditions together can represent human-biometeorological comfort conditions. Physiological equivalent temperature (PET) is used for indexing HTC. 3-hr PET and VP values are calculated based on hourly meteorological data of six selected cities for 18 years (2000-2017) time period. RayMan model has been applied to calculate hourly PETs and VPs. PET and VP data are grouped by frequencies and time period into several classes. Spatial distribution and dispersion characters of biometeorological comfort conditions are measured by statistical techniques. Thermally heat stress is very high in Apr and May. Months of winter indicate the presence of different thermal conditions. Annual comfort is maximum in the coastal city when stressful condition mostly prevails over Krishnanagar (KNG). Puruliya (PRA) shows the driest condition. The obtained information can be applied in planning, healthcare, and tourism sector.

The potential for domestic thermal insulation retrofits on the South African Highveld

The South African Highveld is a portion on the inland plateau characterized by low winter ambient temperatures. Studies done in several climatic regions around the world have found a positive relationship between inadequate housing and low indoor temperatures during the winter season. Prolonged exposure to low indoor temperature is a threat to human physical health. This study characterizes indoor human thermal comfort conditions in typical low-income residential dwellings during the winter season. Mapping indoor human thermal comfort can assist in exploring the potential for domestic thermal insulation retrofits interventions. In-situ temperature measurements were done in 2014, 2016 and 2017 across three Highveld settlements of kwaZamokuhle, kwaDela, and Jouberton. The sample included a mixture of old (pre-1994), post 1994 Reconstruction and Development Programme (RDP) as well as non-RDP structures. Findings were that 88% of sampled dwellings in Jouberton 2016, 86% in Jouberton 2017, 62% in kwaDela and 58% in kwaZamokuhle had daily mean temperatures below the WHO guideline of 18°C. These low indoor temperatures indicate poor insulation in these sampled dwellings. Across all settlements, insulated dwellings had higher daily mean indoor temperatures than non-insulated dwellings. These findings indicate the potential to use thermal insulation retrofits in improving indoor thermal conditions as the majority of dwellings are non-insulated thereby exposing occupants to low indoor temperatures.

On the short-term simulation of heat waves in the Southeast Mediterranean: Sensitivity of the WRF model to various physics schemes

The current study investigated the impact of the Weather Research and Forecasting (WRF) (a) surface layer (SL), (b) land surface and (c) planetary boundary layer (PBL) physics on the short-term simulation of the meteorological and human thermal comfort conditions during 15 heat waves identified between 2004 and 2013 in the southeast Mediterranean and Balkan Peninsula. Four widely used PBL-SL schemes (YSU-MM5, MYJ-Eta, ACM2-Revised MM5, YSU-Revised MM5) and land surface models (LSMs; Noah, Noah-MP, CLM4, RUC) were tested. Comparisons with ground-based observations in 60 measuring sites showed that the WRF model is characterized by a cold bias leading to the underestimation of the extreme heat stress conditions over the entire study region. The MYJ-Eta experiment simulated greater sensible heat fluxes compared to the other PBL-SL scenarios due to the high surface heat exchange coefficient provided by the Eta SL scheme. This contributed to the high MYJ-Eta-modeled daytime 2-m air temperature (T2) and physiologically equivalent temperature (PET) values that were close to the observations. The ACM2 PBL algorithm produced significantly higher PBL heights compared to rest of the tested PBL parameterizations reflecting the strong vertical mixing generated in this scheme. This contributed to the most accurate ACM2-Revised MM5-modeled T2 and PET results in overall. The use of the RUC LSM strengthened significantly the modeled sensible heat fluxes contributing directly to the satisfactory replication of the observed T2 and PET values. However, the RUC-induced enhanced sensible heating relative to the latent heating is may related to a possible underestimation of the soil moisture, as indicated by the notable dry biases during the RUC experiment. Thus, the most accurate T2 and PET results provided by the RUC model may arise from the wrong reason.

A COMPUTATIONAL AND EXPERIMENTAL INVESTIGATION OF AIR FLOW AND CONTAMINANTS CONCENTRATION IN A LABORATORY WITH MIXING VENTILATION SYSTEM

In this research an experimental and computational analysis under Iraqi climate of temperature distribution, velocity and contaminants concentration in the air-conditioned laboratory have been studied for two case studies. Case-I chosen internal combustion engine laboratory of dimensions (10.3 x 8.7 x 3.75) m with a different number of engines used in the experiments and Case-II chosen laboratory of chemical and petroleum products dimensions (3.7x3.6x3.3)m with different locations of the supply air terminal diffuser compared to the existing design situation. ANSYS FLUENT 14 used to simulate the model's laboratories for compared between the present practical work and numerical work results which are acquired by using RNG K-ε and SST k-ω models and found that the SST k-ω model more accurate. The SST (k-w) turbulence model were employed to solve the governing equations numerically with Reynold number 28,933 and validated by comparing the numerical results with experimental data, and this comparison gives a good agreement. The numerical results for case-I compared with experimental data, while for case-II, the numerical results compared with the standard value due to Iraqi cooling code and ASHRAE standards. The results showed that the mixing ventilation system is able to remove various types of pollutants effectively up to 90% in addition to providing human thermal comfort conditions with the effectively of heat removal up to 85% for the state of the internal combustion laboratory. The second case at laboratory of chemical and petroleum products when the supply air terminal diffuser in the same side, the results showed an increase in comfort conditions by up to 40%.Lastly, from the research, it was found that the pollutant transportation and distribution depend in general upon several factors such as type and location of contaminant source, building geometry, the arrangement of air terminal diffuser opening, and thermal/fluid boundary conditions for example flow rate. Numerical simulation of the velocity and diffusion fields in a conventional flow in laboratories is very useful in comprehending flow and diffusion patterns within different changes of the flow conditions.

Erratum to “Seasonal Regional Differentiation of Human Thermal Comfort Conditions in Algeria”

Erratum to “Seasonal Regional Differentiation of Human Thermal Comfort Conditions in Algeria”

Exergy Analysis and Human Body Thermal Comfort Conditions: Evaluation of Different Body Compositions.

This article focuses on studying the effects of muscle and fat percentages on the exergy behavior of the human body under several environmental conditions. The main objective is to relate the thermal comfort indicators with exergy rates, resulting in a Second Law perspective to evaluate thermal environment. A phenomenological model is proposed of the human body with four layers: core, muscle, fat and skin. The choice of a simplified model is justified by the facility to variate the amount of mass in each tissue without knowing how it spreads around the body. After validated, the model was subjected to a set of environmental conditions and body compositions. The results obtained indicate that the area normalization (Watts per square meter) may be used as a safe generalization for the exergy transfer to environment. Moreover, the destroyed exergy itself is sufficient to evaluate the thermal sensation when the model is submitted to environmental temperatures lower than that considered for the thermal neutrality condition (and, in this text, the thermal comfort) . Nevertheless, for environments with temperatures higher than the calculated for the thermal neutrality, the combination of destroyed exergy and the rate of exergy transferred to the environment should be used to properly evaluate thermal comfort.

Effect of different pavements on human thermal comfort conditions

The urban heat island (UHI) phenomenon and outdoor human thermal comfort may be affected by several factors such as the size of the built environment, the rate of open and green spaces and different types of ground surface covers (e.g., grass and artificial covers) in urban areas. Depending on the types and structures of the pavement/covering materials, which can have effects on the albedo and surface heating, ground surfaces reflect solar radiation or heat the air above them. Pavements that can absorb more solar radiation may turn it into heat, thus warming the air, which in turn heats urban areas and make them uncomfortable for human beings. The present study investigates the effect of different materials on the UHI intensity by considering nine different types of materials (andesite, granite, basalt, travertine, impregnated wood, soil, asphalt, clinker powder and grass) in the Ata botanical garden located in the city center of Erzurum, in the Eastern Anatolia region of Turkey. Temperature data were measured on clear summer days during the month of July and compared in terms of thermal comfort. All measurements were taken 150 cm above the ground at 12:00 p.m. by using an infrared thermometer (CEM-DT-8812). In order to estimate the physiologically equivalent temperature (PET) for each soil type, data were analyzed using the RayMan 2.1 software, and the scores were statistically analyzed with analysis of variance (ANOVA). The differences in mean temperatures were evaluated with Fisher’s least significant difference (LSD) test. The results showed that mean PET scores ranged between 28.9 oC for impregnated wood and 25.9 oC for grass (a difference of 3.0 oC), while the other scores were 26.1, 26.7, 27.1, 27.5, 27.8, 28.5 and 28.5 oC for travertine, granite, andesite, soil, clinker powder, basalt, and asphalt, respectively. The analytical results indicated that all the studied materials create a slight heat stress (23.1-29.0 oC) according to their PET indices and their predetermined comfort intervals. However, the levels of heat stress for impregnated wood, asphalt, and basalt were higher than the others. It was determined that grass, travertine and cube granite are optimal surface materials, since they exhibited a level of heat stress that is close to the comfort range (18.1-23.0 oC).